Power quality denotes a degree in which supplied voltage and current deviate from an ideal sine wave, and factors influencing such power quality are divided into instantaneous voltage or current variations, and variations in voltage or current waveforms or harmonic distortion or low-frequency noise appearing for a relatively long time. Here, instantaneous voltage variations (sag, swell, and interruption) and transient voltage belong to the former, and harmonics, overvoltage, and undervoltage belong to the latter.
Fields of power quality diagnosis for analyzing power quality, and determining and predicting the stability of power have attracted attention since the late 80's, and are very interesting and important fields. In particular, in this period, the regulation of the power industry was lifted and high-performance equipment and high-precision systems were developed in foreign countries, so that consumers using power energy started to request the supply of high-quality power enabling their facilities or devices to be continuously and stably operated.
Thereafter, in the late 90's, high-efficiency power electronic devices, high-precision special motors, application semiconductor devices, etc. were developed, and automation equipment, office machines, data communication equipment, etc. based on microprocessors were rapidly developed, so that power quality problems started to attract attention in all fields using power energy, and thus the development of diagnosis analysis systems capable of simply and intuitively diagnosing and analyzing power quality has been required in the same industry.
In particular, in a distribution system, the inspection of the quality of power from a substation to each consumer must be essentially performed, and the selection of the quality monitoring location thereof is very important. If only a distribution system is taken into consideration, the power quality of extra-high power output from a substation, the power quality of secondary sides of a ground transformer and a pole transformer, and the power quality of high-voltage consumer and low-voltage consumer sides are important.
With the development of industry, a distribution system terminal device or main device has also continuously developed, and then the fast processing and transmission of information became possible. Accordingly, when a fault in the distribution system occurs, there is required an abnormal waveform monitoring system capable of measuring online a voltage waveform, a current waveform, and an abnormal power quality waveform in a fault section and allowing a user to rapidly and directly analyze such a fault.
However, such a conventional abnormal waveform monitoring system is problematic in that a Distributed Network Protocol (DNP) used upon measuring a file is vulnerable to the transmission of a large-capacity data file, and thus the system is not suitable for the transmission of a large-capacity data file such as waveform data. That is, the DNP used in the conventional abnormal waveform monitoring system requires a lot of time to transmit large-capacity data, such as a voltage waveform, a current waveform, and an abnormal waveform, so that the time required for the analysis of an abnormal waveform is increased, thus making it impossible to rapidly cope with an abnormal waveform (that is, a fault in a distribution system).